Amplification of BCR Protein Associated with Oncogenesis in Human Hepatocellular Carcinoma

The BCR gene is located on human chromosome 22.The normal cellular BCR gene encodes a 160,000-daltonphosphoprotein associated with a serine/threonine kinaseactivity. The BCR protein is involved in signal transduction. We investigated the expression ofthe BCR protein in hepatocellular carcinoma (HCC),surrounding noncancerous liver tissue, liver cirrhosis(LC), chronic hepatitis (CH), and normal liver with immunohistochemistry and a western blotanalysis. BCR immunoreactivity was detected using amonoclonal antibody. In normal liver, and both CH and LCwithout association of HCC, the immunoreactivity of the BCR protein was minimal. In contrast, 73% (22of 30) of noncancerous liver tissue adjacent to the HCCand 40% (12 of 30) of HCC expressed BCR protein; thisdifference was statistically significant (P < 0.01). The expression of the BCR protein expressioncorrelated with the degree of histologicaldifferentiation of HCC (P < 0.05). In addition, theamplification of BCR protein in noncancerous cells wassupported by the detection of specific protein using awestern blot analysis. In two cases, the expression ofBCR protein occurred only in overtly malignant HCCcells. As a result, the expression of the BCR protein may be associated with oncogenesis in humanHCC.